Egypt suspended all major football games in the country Monday and ordered an investigation into a violent clash in a Cairo suburb between security forces and football (soccer) fans that left more than 20 people dead.

Sunday's violence broke out when police fired tear gas and birdshot into a corridor of fans trying to get into Air Defense stadium on a military facility. President Abdel Fattah el-Sissi ordered the investigation "to uncover the root causes" of the violence.

Fans blamed the police. Authorities said fans suffocated from the tear gas or were trampled in a stampede as they tried to flee the scene. The interior ministry said 22 policemen were also injured and 18 people arrested.

At least one of the victims was buried Monday, with mourners in the streets chanting, "I can hear a martyr's mother screaming, who will avenge my children?"

Fans of Egypt's Zamalek soccer team flock in droves outside the Air Defense Stadium to watch a match between Egyptian Premier League clubs Zamalek and ENPPI in a suburb east of Cairo, Egypt, Sunday, Feb. 8, 2015.

The clash happened at a match between two Cairo clubs, Zamalek and Enppi.The deadliest riot in Egypt soccer history came during a 2012 match when Port Said's Al-Masry team hosted Cairo's Al-Ahly. That riot killed 74 people. Later that year, angry fans burned down the headquarters of Egypt's Football Association, protesting its decision to resume matches before bringing those behind that 2012 riot to justice.

Egypt has curbed the number of people allowed into soccer matches since that riot, prompting fans to often try to storm soccer grounds that they are banned from entering.